Small-Scale Mechanical Testing on Ion Beam and Neutron Irradiated Engineering Materials Peter Hosemann ; D. Frazer, H. Vo, A. Reichardt University of California at Berkeley Nuclear Engineering 1
OUTLINE Introduction/Background Mechanical property changes due to displacement damage Indentation Micro compression testing Micro tensile testing Micro bend testing Non ambient environment Summary 2
Ion beam irradiations and implantation in nuclear engineering
WHY SMALL SCALE MECHANICAL TESTING ? Reactor, Fusion,BLIP and Spallation source Ion beam irradiations irradiations • Material will not be radioactive. • Materials will be radioactive. • Several dpa/day. à Fast • Time consuming, costly, • Cost effective. • Available samples are often limited • Fundamental studies are accessible • Bulk sample irradiation • Limited penetration depth of ions in Small scale mechanical testing: matter. • Add more data points to decrease uncertainty. Small scale mechanical testing: • Mechanical data can be gained from • Local areas are accessible (welds) ion beam irradiated materials. • Additional conditions can be tested on the same sample (temp, env., etc.) Small scale mechanical testing can be useful for both! 4
Micromechanical testing on an ion beam irradiated engineering alloy ION BEAM IRRADIATION OF 304SS
MATERIAL STUDIED AND ION BEAM IRRADIATION G.S.Was and Z. Jiao Univ. Michigan 304SS is the material studied here Samples were provided by UM à 1dpa irradiation and 10 dpa irradiation à 2MeV protons at 360 ° C à Sample material 304SS G.S.Was and Z. Jiao Univ. Michigan
INDENTATION TESTING AT ROOM TEMPERATURE AND ELEVATED TEMPERATURE. Ion beam penetration depth cBN
CROSS SECTION MEASUREMENTS ON ION BEAM IRRADIATED MATERIALS. 2.5 Irradiated IR Depth not irradiated 2 Hardness [GPa] not irradiated 1.5 Nix&Gao fit irradiated Nix and Gao fit 1 0.5 Indentation depth [nm] Un-irradiated Irradiated property 0 property 0 1000 2000 3000 4000 5000
EXAMPLE, CROSS SECTION INDENTATION ON 304 SS IRRADIATED AT UMIBL, QUANTITATIVE DATA 1dpa irradiated at 360C 304 SS (protons) 7 6 5 Hardness (GPa) SRIM calculations 4 10000 9000 3 dose rate [displacements/atom/ion] 1 E-18 H content Atoms/cm3/ions/cm2] 8000 2 Irradiated Control 7000 1 1 E-19 6000 0 0 5 10 15 20 25 30 35 5000 Distance from the surface (um) 1 E-20 H content 4000 A. Lupinacci; P. Hosemann. et al JNM, 2014 displacemtn damage 3000 1 E-21 2000 7 1000 6 1 E-22 0 5 Hardness (GPa) 0 5 10 15 20 25 Depth [um] 4 3 At ion beam dose of 10dpa the beam 2 profile cannot be detected any more. 10dpa irradiated at 360C 304 SS (protons) 1 à Defect saturation 0 0 5 10 15 20 25 30 35 Distance from the sample surface (um)
HIGH TEMPERATURE NANOINDENTATION ON ION BEAM IRRADIATED MATERIALS. (304SS-10DPA) Control Control Resistance thermocouple Resistance thermocouple heater Tracing the hardness of the irradiated and heater Cement unirradiated material over different temperatures using the Micromaterials Indenter. Pendulum assembly Sample AlN tile H. Vo et al. JOM 2015 Water cooled heat shield Insulating base
INDENTATION SIZE EFFECT AND A POSSIBLE APPROACH TO EXTRACT BULK DATA Macro hardness Step 1) Indentation size effect is well known and can be fitted with the Nix and Gao model: H.. Hardness at depth H 0.. hardness at infinite depth h… depth H*…characteristic depth The size effect over temperature is difficult to assess; Assumption: The relative difference between nanohardness and microhardness does not change with temperature. Convert Berkovich Hardness to HV Step 2) H v =0.0947*H nano Relate HV to YS σ y = 2.5 (H v – 68) Step 3) Empirical equations. G.R.Odette et al.
CORRELATING THE NANOINDENTATION TO YS MEASURED BY TENSILE TESTING 800 STRESS [MPa] UTS- Tensile Neutron irradiated and tensile tests vs. Nanoindentation 700 YS-Tensile RT measurements 600 NI-YS Method 1 800H Control RT: h* vs. Temperature Correlation Comparison for Irradiated Alloys 700.0 Calculated vs. Measured Stress 500 600.0 2000 s_Busby_H1000 500.0 s_Busby_H0 s_Milot_H1000 s_Milot_H0 400.0 400 h* s_y s_flow 300.0 1500 Yield, Flow [MPa] 200.0 300 100.0 1000 0.0 200 0 100 200 300 Temperature (°C) 500 100 Grain 1 Grain 2 Temperature (C) Size effect is less pronounced at higher temperature 0 0 0 100 200 300 400 à Underestimation of YS at higher temeprature
MICRO COMPRESSION TESTING ON ION BEAM IRRADIATED 304SS
SAMPLING DIFFERENT AREAS OF THE DOSE PROFILE Grain size typically ~20µm to ~200µm 3 different sets of pillars are manufactured in the same grain and tested using the 20 µm Hysitron PI85 in-situ indenter A. Reichardt et al JNM 2017 Penetration depth
COMPRESSION TEST RESULTS Unirradiated Pillars Irradiated Pillars Irradiated Stopping Point Pillars A. Reichardt et al JNM 2017
POST TESTING SEM IMAGES OF THE PILLARS Not irradiated Stopping peak region 10dpa region A. Reichardt JNM 2017 3 µm Many small slip events occurred. Very few but large slip events occur
LOAD DROPS ANALYSIS A. Reichardt et al JNM 2017 Force Displacement Energy for a load drop Peierls stress: Energy to move a dislocation through the pillar: 1 − 𝜉 ∗ ex p( −2𝜌 𝑒 2𝐻 𝜐 $%&%'() = 1 − 𝜉 𝑐) 𝑋 = 𝜐 $%&%'() ∗ 𝑐 ∗ 𝑚 ∗ 𝑢𝑚 + 𝛿 ∗ 𝑐 ∗ 𝑚 Energy to move the dislocation Surface energy through the pillar # 𝑒𝑗𝑡𝑚𝑝𝑑𝑏𝑢𝑗𝑝𝑜𝑡 = 𝐹𝑜𝑓𝑠𝑧 𝑠𝑓𝑚𝑓𝑏𝑡𝑓𝑒 𝑒𝑣𝑠𝑗𝑜 𝑏 𝑚𝑝𝑏𝑒 𝑒𝑠𝑝𝑞 b=burgers vector, G=shear modulus, γ=surface energy, 𝐹𝑜𝑓𝑠𝑧 𝑢𝑝 𝑒𝑠𝑗𝑤𝑓 𝑝𝑜𝑓 𝑒𝑗𝑡𝑚𝑝𝑑𝑏𝑢𝑗𝑝𝑜 ν=poison ratio, l=pillar width, 𝒕𝒎𝒋𝒒 𝒕𝒖𝒇𝒒 𝒊𝒇𝒋𝒉𝒊𝒖 = # dislocations* burgers vector tl=length of the slip plane
COMPARISON IRRADIATED VS. UNIRRADIATED Not irradiated material: ~200 - 500 dislocations pass through the pillar/slip event à 50-120 nm slip step height K. Farrel et al. 316L 0.78dpa 3 µm ORNL 2002 Irradiated material: ~3500 dislocations pass through the pillar/slip event à 868 nm slip step height TEM 304 10dpa pillar test 3 µm
COMPRESSION TESTING TO EVALUATE FRICTION PARAMETERS IN SiC/SiC COMPOSITES J. Kabel et all Composites B 2017 Matrix FIB trench Interphase Fiber 3µm
IN SITU TESTING OF FIBER/MATRIX INTERFACES Pillar testing: HNLS control Pillar testing: HNLS 11.8dpa HFIR samples
EVALUATING THE FRICTION PARAMETERS 𝑄 U'%VW ∗ 𝑡𝑗𝑜θ = 𝑄 U'%VW ∗ 𝑑𝑝𝑡θ 𝝊 𝒆𝒇𝒄𝒑𝒐𝒆 µ ∗ 𝜈 + τ \%U]^\ 𝐵 𝐵
MICRO TENSILE TESTING ON IRRADIATED MATERIALS
MICRO TENSILE TESTING ON 10DPA 304SS P. Hosemann MRS JMR 2015 PTP device testing Load cycle one Load cycle two 2000 1800 1600 1400 1200 Stress [MPa] 1000 800 Yield: 1544MPa Uniform elongation 600 4% 400 Total elongation 8 % 200 0 0 0.05 0.1 0.15 0.2 0.25 Strain [-]
MICRO TENSILE TESTING ON ION BEAM IRRADIATED 304SS Hi Vo, A. Reichardt G1 tests are all in the same grain unpublished data 2016 G2 tests are all in the same grain 1400 Irr P3 G2 1200 Engineering Stress, σ [MPa] Irr P2, G1 1000 Irr P1, G1 Unirr P3 G2 800 Unirr P2 G1 600 Unirr P1 G1 400 200 0 0 0.1 0.2 0.3 0.4 0.5 0.6 Engineering Strain, ε
NOT OXIDIZED (WITH CARBIDES) AND OXIDIZED GRAIN BOUNDARY Oxidized grain boundary with carbide Unoxidized grain boundary with carbide 25
MICRO BEND TESTING ON IRRADIATED MATERIALS
MICRO 3 POINT BEND TESTING ON HIGHLY IRRADIATED REACTOR RETRIEVED MATERIALS GS3-6 Low Temperature (Sxx) GS3-12 High Temperature (GB)
TAKING IT TO THE NEXT LEVEL-NON AMBIENT CONDITION In-situ Micro bending at 570°C on UO 2 ; D. Frazer In-situ Micro compression testing at -145C A. Lupinacci Acta Mat 2014 D. Frazer 2017 Chilled nitrogen gas (in and out) -145C pillars Cu wires for thermal Cooling contact System Stage Nano- Sample RT pillars SEM Nanoindenter Stage gk indenter Stage
SUMMARY ON MICROMECHANICAL TESTING Outline the importance and potential impact small scale mechanical testing can have to the nuclear materials community Indentation n 10dpa appears to be the saturation dose after which no further hardening can be detected. n Hardness over temperature follows reasonably well the tensile data over temperature. Micro compression testing n Significant slip step differences can be found between irradiated and unirradiated materials. n An energy balance approach to quantify the slip steps is introduced. n Evaluation of fiber/matrix composites. Micro tensile testing: n A significant difference between the irradiated and unirradiated strain can be observed failure mode as well as quantitative numbers.
Thank you for your attention! Slide 31
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